from
Bouvier's Law Dictionary, Revised 6th Ed (1856)
DOUBLE VOUCHER. A common recovery is sometimes suffered with double voucher,
which occurs when the person first vouched to warranty, comes in and vouches
over a third person. See a precedent, 2 Bl. Com. Appx. No. V. p. xvii.;
also, Voucher.
2. The necessity for double voucher arises when the tenant in tail is
not the tenant in the writ, but is tenant by warranty; that is, where he is
vouched, and comes in and confesses the warranty. Generally speaking, to
accomplish this result, a previous conveyance is necessary, by the tenant in
tail, to a third person, in order to make such third person tenant to a writ
of entry. Preston on Convey. 125-6.